Mask forming methods and a field emission display emitter mask forming method

ABSTRACT

The present invention includes structures, lithographic mask forming solutions, mask forming methods, field emission display emitter mask forming methods, and methods of forming plural field emission display emitters. One aspect of the present invention provides a mask forming method including forming a masking layer over a surface of a substrate; screen printing plural masking particles over a surface of the masking layer; and removing at least portions of the masking layer using the masking particles as a mask. Another aspect of the present invention provides a method of forming plural field emission display emitters. This method includes forming a masking layer over an emitter substrate; screen printing a plurality of masking particles over the masking layer; removing portions of the masking layer intermediate the screen printed masking particles to form a plurality of masking elements; removing the masking particles from the masking elements; and removing portions of the emitter substrate to form plural emitters.

RELATED PATENT DATA

This patent resulted from a continuation application of U.S. patentapplication Ser. No. 09/141,809, filed Aug. 28, 1998, now U.S. Pat. No.6,228,538, entitled “Mask Forming Methods and Field Emission DisplayEmitter Mask Forming Methods”, naming John J. Michiels et al. asinventors and the disclosure of which is incorporated by reference.

PATENT RIGHTS STATEMENT

This invention was made with Government support under Contract No.DABT63-97-C-0001 awarded by Advanced Research Projects Agency (ARPA).The Government has certain rights in this invention.

TECHNICAL FIELD

The present invention relates to structures, lithographic mask formingsolutions, mask forming methods, field emission display emitter maskforming methods, and methods of forming plural field emission displayemitters.

BACKGROUND OF THE INVENTION

Field emission displays are utilized in a variety of displayapplications. Conventional field emission displays include a cathodeplate having a series of emitter tips fabricated thereon. The tips areconfigured to emit electrons toward a phosphor screen to produce animage. The emitters or emitter tips are typically formed from an emittermaterial such as conductive polysilicon, molybdenum, or aluminum.Multiple emitters are typically utilized to excite a single pixel. Forexample, 120 emitters may be used for a single pixel. Individual pixelscontain a deposited one of red, green, or blue phosphor.

One method of fabrication of emitter tips is described in U.S. Pat. No.5,391,259 (the '259 patent); assigned to the assignee hereof andincorporated by reference. A hardmask layer is formed over emittermaterial in the disclosed fabrication method. Portions of the hardmasklayer are selectively removed to form a hardmask utilized for emitterfabrication. One conventional method utilizes photolithography andetching to selectively remove portions of the hardmask layer. Followingthe formation of the hardmask, the emitter material is etchedisotropically to form the tips. For proper fabrication, it is highlydesired that hardmasks be patterned to a consistent critical dimension.Variations in critical dimensions or size of the hardmasks can result innon-uniformity within the formed emitter tips.

One method for fabricating the hardmask utilized to form the emittertips uses spheres or beads as the mask for creating the hardmask layermask. The spheres are provided in a liquid medium such as water. Theemitter substrate is dipped into a vat of solution containing thespheres. The substrate is then withdrawn from the solution and some ofthe spheres adhere to the emitter substrate.

It is preferred to achieve a homogeneous/uniform distribution of beadsupon the face of the emitter material. However, homogeneous distributionhas been difficult to achieve. A non-uniform distribution of beads canresult in adjacent spheres touching and subsequent adjoining of emittertips following emitter fabrication causing problems with electron optics(e.g., focusing of electrons). Such joining of emitter tips can resultin the emission of electrons which strike adjacent phosphor patchesresulting in poor color intensity and poor color distribution.

Further, the spheres may exhibit poor adhesion to the surface of thesubstrate when conventional methods of applying the spheres to thesubstrate surface are utilized. This drawback is particularly acute ifthe spheres are larger than 0.5 microns.

The present invention provides improvements in device fabrication whileavoiding problems experienced in the prior art.

SUMMARY OF THE INVENTION

The present invention includes structures, lithographic mask formingsolutions, and mask forming methods. The invention further includesfield emission display emitter mask forming methods and methods offorming plural field emission display emitters.

One aspect of the present invention provides a lithographic mask formingsolution. The solution includes a photosensitive material and aplurality of masking particles within the photosensitive material. Thephotosensitive material comprises photoresist and the masking particlescomprise beads or spheres in exemplary embodiments. The photosensitivematerial is cured and portions of the cured photosensitive material areremoved in preferred aspects of the invention. Masking particlesremaining upon the substrate are thereafter used as a mask to process asubstrate. Uncured photosensitive material is used to improve adhesionof masking particles to the substrate to be processed.

A second aspect of the invention provides a structure forming methodincluding providing a solution comprising a photosensitive material anda plurality of masking particles. The method also provides applying thesolution over a substrate and removing at least a portion of thephotosensitive material while leaving the masking particles over thesubstrate. The solution is preferably screen printed. The method alsoincludes processing the substrate using the masking particles as a mask.

According to another aspect, a method of forming a mask over a substrateincludes forming a masking layer over a surface of a substrate. Maskingparticles are screen printed over a surface of the masking layer andportions of the masking layer are removed using the masking particles.The removing of portions of the masking layer forms a mask. This maskincludes a plurality of circular masking elements in some embodiments.

In another aspect, masking particles are mixed within photoresist toform a solution which can be screen printed. The screen printingincludes printing masking particles within the solution containingphotoresist. In one embodiment, the solution has a concentration withinthe approximate range of approximately 1×10⁸-1×10⁹ masking particles permilliliter of photoresist.

It is preferred to provide a uniform layer of masking particles upon themasking layer. To this end, screen printing of masking particles guidesthe masking particles to predefined regions over the substrate. Further,the masking particles are preferably agitated to space the maskingparticles from one another.

In some aspects of the invention, the solution is permitted to cure andportions of the photoresist or other photosensitive material is removed.The masking particles form a mask utilized to form a hardmask from themasking layer. The hardmask is subsequently utilized to form a randomarray of emitters of a field emission display from an emitter substrate.

BRIEF DESCRIPTION OF THE DRAWINGS

Preferred embodiments of the invention are described below withreference to the following accompanying drawings.

FIG. 1 is a cross-sectional view of a structure including a substrateand a solution layer during processing of the structure.

FIG. 2 is a cross-sectional view of a processing step of the structuresubsequent to the step of FIG. 1.

FIG. 3 is a cross-sectional view of a processing step of the structuresubsequent to the step of FIG. 2.

FIG. 4 is a cross-sectional view of a segment of a field emissiondisplay having plural emitters fabricated in accordance with processesof the present invention.

FIG. 5 is a cross-sectional view of a substrate, masking layer, layer ofsolution and a screen during fabrication of a backplate of a fieldemission display.

FIG. 6 is a diagrammatic representation of conventional offset screenprinting.

FIG. 7 is a diagrammatic representation of contact screen printing.

FIG. 8 is a top plan view of a predefined region shown at the processingstep of FIG. 5.

FIG. 9 is a cross-sectional view of a processing step for forming thebackplate subsequent to the step of FIG. 5.

FIG. 10 is a cross-sectional view of a processing step of the backplatesubsequent to the step of FIG. 9.

FIG. 11 is a cross-sectional view of a processing step of the backplatesubsequent to the step of FIG. 10.

FIG. 12 is a cross-sectional view of a processing step of the backplatesubsequent to the step of FIG. 11.

FIG. 13 is a cross-sectional view of a processing step of the backplatesubsequent to the step of FIG. 12.

FIG. 14 is a cross-sectional view of emitters formed from an emittersubstrate of a field emission display in accordance with the presentinvention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

This disclosure of the invention is submitted in furtherance of theconstitutional purposes of the U.S. Patent Laws “to promote the progressof science and useful arts” (Article 1, Section 8).

The present application is described with reference to fabricationtechniques for structures which comprise electronic components ordevices. Exemplary electronic components are fabricated fromsemiconductive substrates or substrates for flat panel or field emissiondisplay (FED) devices. Such substrates can comprise silicon, glass,quartz or other materials. Structures are processed and subsequentlyutilized in electronic devices of various configurations.

During formation of structures such as semiconductive components or FEDemitters, it is often necessary to form masks for various processingsteps. The masks can be utilized to process into a substrate or formadditional layers upon the substrate. Certain aspects of the presentinvention are directed towards the formation of lithographic masks andthe formation of solutions utilized to form lithographic masks.

Referring to FIG. 1, a structure 1 is illustrated. Processing ofstructure 1 is described with reference to formation of an electronicdevice or component. For example, structure 1 is processed to comprise atransistor, memory cell, discrete component, such as a resistor or FEDemitters in exemplary applications. Structure 1 is fabricated for use inelectronic devices in some applications.

The depicted structure 1 comprises a substrate 2 and a solution layer 3formed over substrate 2. Substrate 2 comprises a semiconductivesubstrate, such as monocrystalline silicon, in some embodiments. Inparticular, substrate 2 can comprise a field emission display substrateas described below. Alternatively, substrate 2 comprises other materialssuitable for forming electronic devices or components.

Solution layer 3 comprises a medium 4 and a plurality of maskingparticles 5 within medium 4. In a preferred embodiment, medium 4comprises a photosensitive resin or material. Solution layer 3 can beformed to comprise the same solution layer as described below withreference to FIG. 5 (i.e., solution layer 42). Utilizing such asolution, masking particles 5 comprise spheres and photosensitivematerial 4 comprises photoresist. The solution is formed in theexemplary embodiment to have a concentration within an approximate rangeof 1×10⁸-1×10⁹ masking particles per milliliter of photosensitivematerial or photoresist.

In the presently described embodiment, solution layer 3 can be appliedover substrate 2 by any suitable method, such as screen printing.Conventional offset and contact screen printing methods are describedbelow with reference to FIG. 6 and FIG. 7. Such printing techniques areutilized in exemplary processing methods to form solution layer 3. Asdescribed in detail below, screen printing solution layer 3 is preferredto provide a uniform distribution of spheres within layer 3 and oversubstrate 2.

Following provision of solution layer 3 over substrate 2, medium 4comprising photosensitive material is cured or developed. Exemplarycuring methods include exposing solution layer 3 to ultraviolet light ifmedium 4 comprises positive photoresist.

Referring to FIG. 2, portions of photosensitive medium 4 are removedfollowing curing of exposed portions of medium 4. In particular, curedportions of photosensitive material 4 can be stripped or otherwiseremoved. Masking particles 5 remain over substrate 2 following theremoval of cured portions of medium 4.

Feet or small portions 6 of photosensitive medium 4 remain intermediateindividual masking particles 5 and substrate 2 following removal ofexposed portions of the photosensitive material. Uncured remaining resinfeet 6 assist with adhering respective masking particles 5 to substrate2.

Removal of exposed portions of photosensitive medium 4 forms a mask 7comprising masking particles 5 and feet 6. Mask 7 comprises alithographic mask for processing of structure 1 in the describedembodiment. In particular, masking particles 5 and corresponding feet 6of mask 7 define exposed regions 8 upon substrate 2. Exposed regions 8of substrate 2 can be processed in subsequent fabrication steps.

Referring to FIG. 3, an exemplary fabrication step of structure 1 isdescribed. In particular, substrate 2 is processed using maskingparticles 5 and feet 6 of mask 7 as a lithographic mask. In FIG. 3,plural diffusion regions 9 are formed within substrate 2. Exemplarydiffusion regions can comprise p type or n type diffusion regionsdepending upon the particular structure 1 being processed.

Such diffusion processing is exemplary and other processing steps suchas deposition can occur using mask 7. Following formation of diffusionregions 9, or other alternative processing, masking particles 5 and feet6 can be stripped from substrate 2. Acetone is utilized in oneembodiment to strip masking particles 5 and feet 6.

Referring to FIG. 4-FIG. 14, methods of forming masks are described withreference to field emission display devices. Further, methods of formingfield emission display emitters are described. The invention is notlimited to field emission display device fabrication as described in thefollowing embodiments and applications. Aspects of the present inventiondescribed below might be utilized within any masking and etchingprocess.

Referring to FIG. 4, an exemplary portion of a field emission display 10is depicted. The illustrated portion of the field emission display 10includes a display segment 12. Display segment 12 is capable ofdisplaying a pixel of information, or a portion of a pixel. For example,display segment 12 may be configured to display one green dot of ared/green/blue full-color triad pixel. Field emission display 10includes a faceplate or screen 24 and a cathode plate or baseplate 28spaced therefrom. Support structures or separators 30 space faceplate 24from baseplate 28 and generally define segment 12 in the illustratedembodiment.

Baseplate 28 of the described embodiment comprises a matrix addressablearray of cathode emission structures or emitters 16. Baseplate 28additionally includes an emitter substrate 14, upon which the emissionstructures 16 are created, a dielectric insulating layer 26, and ananodic grid 18.

Emitter substrate 14 has been patterned and etched to formmicro-cathodes or emitters 16 as described in detail below. Displaysegment 12 includes plural field emission sites 15. Sites 15 correspondto the emitters 16. Dielectric insulating layer 26 is formed uponsubstrate 14 intermediate emitters 16 and sites 15. More specifically,insulator 26 has plural openings at the field emission sites 15. Avacuum is created between faceplate 24 and baseplate 28 to provideproper functioning of plural emitters 16 of the described field emissiondisplay 10. Separators 30 function to support atmospheric pressure whichexists on electrode faceplate 24 as a result of the vacuum.

Emitters 16 are constructed on top of emitter substrate 14. Emitters 16are integral with emitter substrate 14 and individually comprise acathode for emission of electrons. Alternatively, emitters 16 formcathodes from one or more deposited conductive films, such as a chromiumamorphous silicon bilayer. Emitters 16 preferably have a finemicro-point in the described embodiment.

Grid structure 18 surrounds emission sites 15 in the describedembodiment. A power source 20 is utilized to apply a voltagedifferential, between the cathodes (emitters 16) and anodic grid 18. Inparticular, emitters 16 are individually electrically coupled with anegative terminal of source 20. A positive terminal of source 20 iscoupled with grid 18. Grid 18 serves as a structure for applying anelectrical field potential to appropriate emitters 16. A stream ofelectrons 22 is emitted from emitters 16 responsive to the applicationof a voltage differential via grid 18.

A second positive terminal of source 20 is connected with faceplate 24thereby forming another anode. Faceplate 24 includes a phosphor coating25 over surface facing emitters 16. Electrons ejected from emitters 16are aimed toward faceplate 24. Further details of field emissiondisplays are described in U.S. Pat. Nos. 5,229,331 and 5,391,259, bothincorporated herein by reference.

Referring to FIG. 5, fabrication of an exemplary portion of baseplate 28of a field emission display is shown. In particular, methods of formingfield emission display masks utilized for formation of emitters 16 aredescribed. Methods of forming emission display emitters 16 are alsodescribed. The formed emitters 16 are conical in the describedembodiment. Emitters 16 may comprise protuberances of other shapes inother embodiments.

The illustrated baseplate 28 includes emitter substrate 14, a maskinglayer 40 and a layer of solution 42. A single crystal silicon layerserves as substrate 14 in one embodiment. Amorphous silicon orpolysilicon deposited upon a glass substrate are other examples. Othermaterials are utilized in other embodiments. In particular, substrate 14of FIG. 5 can be any material from which emitters 16 can be fabricated.

Masking layer 40, also referred to as a hardmask layer, comprises amasking layer substrate which is deposited or grown on substrate 14 inthe described embodiment. An example material for layer 40 is silicondioxide. Masking layer 40 preferably has a thickness great enough toavoid being completely consumed during subsequent etching processes. Itis also desired to provide a masking layer 40 which is not excessivelythick so as to overcome adherent forces which maintain the masking layerin the correct position with respect to emitters 16 throughout theemitter fabrication process as described hereafter. An exemplary rangeof thicknesses of masking layer 40 is 0.05-0.5 microns with a thicknessof 0.2 microns being preferred.

Solution layer 42 comprises a plurality of masking particles 46 within amedium 48. In one embodiment, masking particles 46 are initially mixedinto a fairly viscous or thixotropic medium 48. Medium 48 is preferablyliquid having an operable viscosity range from 10 to 1100 centipoise. Aviscosity range from 40 to 200 centipoise is preferred at roomtemperature. Solution layer 42 is screen printed onto a surface ofmasking layer 40 and subsequently cured. As described below, medium 48is thereafter removed providing an etch mask for fabricating anothermask used to form a random array of field emitter tips (i.e., emitters).

Masking particles 46 preferably comprise spherical members and medium 48comprises photoresist or photo sensitive material such as polyimide.Example materials are polystyrene or latex for spheres 46 and positivephotoresist for medium 48. Masking particles 46 have an exemplarydiameter of approximately one micron (0.04 mils). A preferred sphericaldiameter range is from 0.5 to 2.0 microns.

Masking members or particles 46 are typically provided in a watersolution having a density of approximately 10¹¹ beads or spheres permilliliter (ml) of solution. Exemplary bead solutions are available fromBangs Labs IDC Corp. The water solution containing the beads or maskingparticles 46 is dissolved in a carrier, such as isopropyl alcohol, andsubsequently combined or mixed with photoresist in one embodiment of theinvention. In one example, two cubic centimeters (cc) of isopropylalcohol were added per one cubic centimeter of bead solution. Then, fivecubic centimeters of photoresist were combined with this solutionproviding a ratio of 1:2:5 by volume. An exemplary ratio range of beadsolution to isopropyl alcohol to photoresist is 1:(2 20):(5 50).

A 1:2:5 mixture of solution yields a bead or masking particle density ofapproximately 1.25×10¹⁰ beads per milliliter of solution. An exemplarypreferred concentration of masking particles 46 within medium 48 iswithin the approximate range of 1×10⁸-1×10⁹ beads/ml immediately priorto screen printing upon hardmask masking layer 40.

In one example, approximately 1×10¹¹ spheres were mixed intoapproximately 300 ml of Olin HPR504 resist comprising medium 48. Thesolution containing spheres 46 and medium 48 was screen printed onto aglass substrate using conventional screen printing to form solutionlayer 42. A 400 mesh screen having a wire diameter of 0.00075 incheswith a patterned emulsion coating of 0.0002 inches was utilized for thescreen printing.

A screen 44 is utilized to screen print the solution layer 42 inaccordance with the described embodiment of the present invention. It isdesired to provide solution layer 42 upon masking layer 42 having auniform density of masking particles 46. It is also preferred to providespacing between adjacent masking particles 46.

Screen 44 includes plural mesh portions 45 (one whole mesh portion 45 isshown in FIG. 5). Mesh portions 45 of screen 44 define predefinedregions 50 over masking layer 40 and emitter substrate 14 (onepredefined region 50 corresponding to the illustrated mesh portion 45 isshown in FIG. 5). Screen 44 includes mesh portions 45 individuallyhaving dimensions of 1.75 mils by 1.75 mils square in one example.Screen 44 is thin as possible in preferred embodiments. An exemplarypreferred thickness for a cured layer 42 is about five microns.

Referring to FIG. 6, conventional offset screen printing of solution toform solution layer 42 is shown. A squeegee 41 is used to urge solutionthrough mesh portions of screen 44. Solution is deposited onto screen 44in front of the direction of travel of squeegee 41 in the describedembodiment. Screen 44 and masking layer 40 are spaced by a distance d₁(e.g., 0.04 inches). Squeegee 41 passes laterally over screen 44 andpresses screen 44 to contact the layer being printed upon (e.g., maskinglayer 40). Squeegee 41 simultaneously forces the solution containingmasking particles through mesh portions of screen 44.

Referring to FIG. 7, contact printing of the solution to form solutionlayer 42 upon masking layer 40 is shown. Screen 44 contacts maskinglayer 40 when contact printing is utilized. Squeegee 41 passes laterallyover screen 44 forcing the solution containing the masking particlesthrough mesh portions of screen 44. Conventional offset printing is thepreferred screen printing method.

Referring to FIG. 8, a top view of solution layer 42 and screen 44 areshown. Plural mesh portions 45 (shown in phantom) are defined by screen44. Screen 44 also defines plural regions 50 over the masking layer andthe emitter substrate (the emitter substrate and the masking layer arebelow solution layer 42 and not shown in FIG. 8). Predefined regions 50correspond to mesh portions 45 in the illustrated embodiment. Inaccordance with one aspect of the present invention, mesh portions 45 ofscreen 44 operate to guide masking particles 46 to respective predefinedregions 50 over emitter substrate 14 and masking layer 40. The prior artis not understood to disclose any mechanism to guide masking particlesover the region(s) to be covered with masking particles.

FIG. 8 illustrates an exemplary number of masking particles 46 withinrespective predefined regions 50. More or less masking particles 46 canbe provided within individual predefined regions 50. In a preferredembodiment, a two micron pitch of masking particles 46 is desired ifmasking particles 46 having a diameter of one micron are utilized. Inthis embodiment, the approximate number of masking particles 46 receivedthrough one mesh portion 45 is the area of the mesh portion in squaremicrons divided by four. Further, FIGS. 5 and 8 diagrammaticallyillustrate screen printing of masking particles 46 and are not to scale.

Referring to FIG. 9, screen 44 is removed from backplate segment 28following formation of solution layer 42 over emitter substrate 14.Screen 44 is ideally removed before substantial curing of solution layer42. Masking particles 46 and medium 48 flow to fill the void created bythe removal of screen 44.

Backplate segment 28, including emitter substrate 14, masking layer 40and solution layer 42, is preferably agitated following removal ofscreen 44 and prior to substantial curing. Such agitation encouragesmovement of masking particles 46 apart from one another and providesspacing intermediate adjacent masking particles 46. Such agitation alsoencourages settling of masking particles 46 upon masking layer 40.Masking particles 46 may also adhere to masking layer 40 followingcontacting of the same. Subsequently, solution layer 42 is cured. Anexample curing process includes air drying backplate 28 for twentyminutes in ambient air at 50% humidity. Masking particles 46 defineintermediate portions 54 of medium 48 between adjacent masking particles46.

Referring to FIG. 9 and FIG. 10, following curing of solution layer 42,medium 48, including intermediate portions 54 thereof, is stripped orotherwise removed. In embodiments where medium 48 comprises positivephotoresist, baseplate segment 28 is flood exposed to ultraviolet lightand developed. Media 48, including intermediate portions 54, isthereafter stripped. A foot or small portion 52 of medium 48 can remainintermediate individual masking particles 46 and masking layer 40. Feet52 of medium 48 are defined by the diameter of respective maskingparticles 46. Masking particles 46 preferably contact masking layer 40.Remaining portions of medium 48 or feet 52 assist with adhesion of basesof masking particles 46 to masking layer 40. Masking particles 46 andfeet 52 form a mask 59 upon masking layer 40. In particular, maskingparticles 46 and feet 52 define plural exposed portions or regions 58 ofmasking layer 40.

Referring to FIG. 10 and FIG. 11, exposed portions 58 of masking layer40 are removed from emitter substrate 14 using spheres 46 as mask 59. Inone embodiment, anisotropic etching is utilized. An example chemistryincludes CF₄, CHF₃, Ar₂ as described in the '259 patent. Such removal ofexposed portions 58 of masking layer 40 provides masking elements 56beneath masking particles 46. Masking elements 56 substantiallycorrespond to, or are defined by, the diameters of respective maskingparticles 46. Masking elements 56 are circular in the describedembodiment. Utilization of masking particles 46 in accordance with thepresent invention improves critical dimension control while producingmasking elements 56.

Referring to FIG. 12, the beads or masking particles and the feet havebeen stripped from masking elements 56. Acetone is utilized in oneembodiment to strip the masking particles and feet. Masking elements 56define a mask 57, which is also referred to herein as a hardmask.Masking elements 56 define exposed regions or portions 60 of emittersubstrate 14. Exposed portions 60 are intermediate masking elements 56.

Referring to FIG. 13, portions of emitter substrate 14, includingexposed portions 60, have been etched (preferably substantiallyisotropically) to form plural emitters 16. An example etching chemistryis SF₆, Cl₂, He as set forth in the '259 patent. Emitters 16 are formedcorresponding to circular masking elements 56. A timed etch is utilizedto form emitters 16 in one embodiment.

Referring to FIG. 14, a substantially uniform array 62 of emitters 16 isshown upon emitter substrate 14. The insulating dielectric layer may besubsequently formed to fabricate the backplate 28 shown in FIG. 4.Additionally, the anodic grid may be provided enabling control of theemission of electrons from emitters 16.

In compliance with the statute, the invention has been described inlanguage more or less specific as to structural and methodical features.It is to be understood, however, that the invention is not limited tothe specific features shown and described, since the means hereindisclosed comprise preferred forms of putting the invention into effect.The invention is, therefore, claimed in any of its forms ormodifications within the proper scope of the appended claimsappropriately interpreted in accordance with the doctrine ofequivalents.

What is claimed is:
 1. A mask forming method comprising: providing asolution including photosensitive material and a plurality of maskingparticles within the photosensitive material; applying the solution overa substrate; curing at least a portion of the photosensitive materialapplied over the substrate; and removing cured photosensitive materialwhile leaving the masking particles over the substrate.
 2. The methodaccording to claim 1 wherein the applying comprises screen printing thesolution over the substrate.
 3. The method according to claim 1 whereinthe applying comprises applying the solution over the substratecomprising a semiconductive substrate.
 4. The method according to claim1 wherein the applying comprises applying the solution over thesubstrate comprising a masking layer substrate.
 5. The method accordingto claim 1 further comprising adhering the masking particles over thesubstrate using the photosensitive material.
 6. The method according toclaim 1 wherein the providing comprises providing the solution includingphotosensitive material comprising photoresist.
 7. A mask forming methodcomprising: forming a masking layer over a surface of a substrate;screen printing plural masking particles over a surface of the maskinglayer; and removing at least portions of the masking layer using themasking particles as a mask.
 8. The method according to claim 7 whereinthe screen printing is offset screen printing.
 9. The method accordingto claim 7 further comprising removing the masking particles followingthe removing.
 10. The method according to claim 7 further comprisingagitating the masking particles following the screen printing.
 11. Themethod according to claim 7 wherein the screen printing comprisesprinting spherical masking particles.
 12. The method according to claim7 wherein the screen printing comprises printing masking particleswithin a solution containing photoresist.
 13. The method according toclaim 12 further comprising: curing the photoresist; and removingportions of the photoresist from over the masking particles and maskinglayer.
 14. The method according to claim 12 wherein the screen printingcomprises printing masking particles within a solution having aconcentration within an approximate range of 1×10⁸-1×10⁹ maskingparticles per milliliter of photoresist.
 15. The method according toclaim 7 further comprising guiding the masking particles over predefinedregions of the masking layer by the screen printing.
 16. The methodaccording to claim 7 wherein the removing forms discrete circularmasking elements.
 17. The method according to claim 7 wherein theremoving comprises anisotropically etching the masking layer.
 18. Themethod according to claim 7 wherein the forming comprises forming themasking layer over the surface of the substrate comprising an emittersubstrate of a field emission display.
 19. A mask forming methodcomprising: forming a masking layer over a surface of a substrate;forming a solution layer comprising a liquid medium and a plurality ofmasking particles over a surface of the masking layer and providing themasking particles over predefined regions of the substrate during theforming the solution layer; removing at least portions of the maskinglayer using the masking particles as a mask; and wherein the providingcomprises printing the masking particles using a screen.
 20. The methodaccording to claim 19 further comprising removing the masking particlesfollowing the removing.
 21. The method according to claim 19 furthercomprising agitating the masking particles following the providing. 22.The method according to claim 19 wherein the providing comprises screenprinting masking particles within a solution containing photoresist. 23.The method according to claim 22 further comprising: curing thephotoresist; and removing portions of the photoresist from over themasking particles and masking layer.
 24. The method according to claim19 wherein the removing comprises anisotropically etching the maskinglayer.
 25. The method according to claim 19 wherein the formingcomprises forming a masking layer over an emitter substrate of a fieldemission display.
 26. A mask forming method comprising: forming amasking layer over a surface of a substrate; forming a layer of solutionincluding plural masking particles over a surface of the masking layer;guiding the masking particles to predefined regions over the substrateusing a screen; and removing at least portions of the masking layerusing the masking particles as a mask.
 27. The method according to claim26 further comprising agitating the masking particles following theguiding.
 28. The method according to claim 26 wherein the forming amasking layer comprises forming a masking layer over an emittersubstrate of a field emission display.
 29. The method according to claim26 wherein the forming the layer of solution comprises screen printingmasking particles within photoresist.
 30. The method according to claim29 further comprising: curing the photoresist; and removing portions ofthe photoresist from over the masking particles and masking layer. 31.The method according to claim 26 wherein the removing comprisesanisotropically etching the masking layer.
 32. A field emission displayemitter mask forming method comprising: forming a masking layer over asurface of an emitter substrate; printing a layer of masking particlesover a surface of the masking layer using a screen and a squeegee;removing portions of the masking layer intermediate the screen printedmasking particles; and removing the masking particles from remainingportions of the masking layer following the removing of portions of themasking layer.
 33. The method according to claim 32 further comprisingremoving the screen following the printing and prior to the removing theportions of the masking layer.
 34. The method according to claim 32further comprising agitating the masking particles following theprinting.
 35. The method according to claim 32 wherein the printingcomprises printing the masking particles within a solution containingphotoresist.
 36. The method according to claim 35 further comprising:curing the photoresist; and removing portions of the photoresist fromover the masking particles and masking layer.
 37. The method accordingto claim 32 wherein the removing portions of the masking layer comprisesanisotropically etching the masking layer.
 38. The method according toclaim 7 wherein the screen printing comprises physically contacting theplural masking particles to urge the masking particles through a screen.39. The method according to claim 7 wherein the screen printingcomprises offset printing.
 40. The method according to claim 7 whereinthe screen printing comprises physically contacting a screen with asqueegee to urge the plural masking particles through a screen.
 41. Themethod according to claim 19 wherein the forming the solution layercomprises forming the solution layer having a substantially uniformthickness.
 42. The method according to claim 19 wherein the forming thesolution layer comprises forming the solution layer comprising acontinuous layer over substantially an entire portion of the substrateto be processed.
 43. The method according to claim 19 wherein theforming the solution layer comprises providing all the masking particleswithin a single continuum of liquid medium over the masking layer. 44.The method according to claim 26 wherein the forming the layer ofsolution comprises forming the layer having a substantially uniformthickness.
 45. The method according to claim 26 wherein the forming thelayer of solution comprises forming the layer comprising a continuouslayer over substantially an entire portion of the substrate to beprocessed.
 46. The method according to claim 26 wherein the forming thelayer of solution comprises providing all the masking particles within asingle continuum of liquid medium over the masking layer.
 47. The methodaccording to claim 32 wherein the printing comprises offset printing.48. The method according to claim 19 further comprising selecting thepredefined regions of the substrate before the forming.
 49. A maskforming method comprising: forming a masking layer over a surface of asubstrate; forming a solution layer comprising a liquid medium and aplurality of masking particles over a surface of the masking layer andproviding the masking particles over predefined regions of the substrateduring the forming the solution layer; removing at least portions of themasking layer using the masking particles as a mask; and wherein theproviding comprises screen printing masking particles within a solutioncontaining photoresist.
 50. The method of claim 49 further comprising:curing the photoresist; and removing portions of the photoresist fromover the masking particles and masking layer.
 51. A mask forming methodcomprising: forming a masking layer over a surface of a substrate;forming a solution layer comprising a liquid medium and a plurality ofmasking particles over a surface of the masking layer and providing themasking particles over predefined regions of the substrate during theforming the solution layer; removing at least portions of the maskinglayer using the masking particles as a mask; and selecting thepredefined regions of the substrate before the forming the solutionlayer.